This proposal is a request for continuation of research Grant NS 12365. Venom from the scorpion Centruroides sculpturatus contains a large number of low molecular weight proteins (7000 daltons, approximately) that vary greatly in their toxicities and to a lesser extent in their mechanism of action. The objectives of the present research are to learn where the toxins bind; how they bind to the receptive call; what are the effects are as a consequence of their binding; and what might be done to reverse the otherwise irreversible binding of the toxins to cells. Selected toxins isolated from the venom will be used in these studies. The effects of chemically modifying certain side chain groupings will be studied. Cross-reactions of immune sera likewise will be investigated as part of the overall study relating structure to function in this group of neurotoxins.